[PATCH 2/2] swiotlb: allow architectures to override swiotlb pool allocation

[Jeremy Fitzhardinge <jeremy@goop.org>]

Architectures may need to allocate memory specially for use with
the swiotlb.  Create the weak function swiotlb_alloc_boot() and
swiotlb_alloc() defaulting to the current behaviour.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Joerg Roedel <joerg.roedel@amd.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
---
 include/linux/swiotlb.h |    3 +++
 lib/swiotlb.c           |   15 ++++++++++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

===================================================================
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -2,6 +2,9 @@
 #define LINUX__SWIOTLB_H
 
 #include <asm/swiotlb.h>
+
+extern void *swiotlb_alloc_boot(size_t bytes);
+extern void *swiotlb_alloc(unsigned order);
 
 /* SWIOTLB interface */
 
===================================================================
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -127,6 +127,16 @@
 __setup("swiotlb=", setup_io_tlb_npages);
 /* make io_tlb_overflow tunable too? */
 
+void * __weak swiotlb_alloc_boot(size_t size)
+{
+	return alloc_bootmem_low_pages(size);
+}
+
+void * __weak swiotlb_alloc(unsigned order)
+{
+	return (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN, order);
+}
+
 /*
  * Statically reserve bounce buffer space and initialize bounce buffer data
  * structures for the software IO TLB used to implement the DMA API.
@@ -146,7 +156,7 @@
 	/*
 	 * Get IO TLB memory from the low pages
 	 */
-	io_tlb_start = alloc_bootmem_low_pages(bytes);
+	io_tlb_start = swiotlb_alloc_boot(bytes);
 	if (!io_tlb_start)
 		panic("Cannot allocate SWIOTLB buffer");
 	io_tlb_end = io_tlb_start + bytes;
@@ -203,8 +213,7 @@
 	bytes = io_tlb_nslabs << IO_TLB_SHIFT;
 
 	while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
-		io_tlb_start = (char *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
-		                                        order);
+		io_tlb_start = swiotlb_alloc(order);
 		if (io_tlb_start)
 			break;
 		order--;